The Very Basics
Hi everyone! My name is Judy Xu from Shanghai, China. I study at the international department (IB curriculum) of Shanghai World Foreign Language Academy, and will be entering my junior year in fall. In my free time I like to watch TV Dramas/Movies, listen to music, play with coloring books and play badminton.
Biological Research@BLI
I am very passionate about Biology. Especially, I always get fascinated by the emergent property of human bodies where body parts play different roles, but they “corporate” with each other as a system. It seems to me that the unique functions of each body part work like a puzzle – every pieces match with another perfectly. Furthermore, I am also impressed by how the progresses in DNA technologies give tiny double helixes the ability to solve significant problems around us – which is exactly what our course is going to focus on!! Nevertheless, with limited academic opportunities for me to explore my interests in these advanced fields in school, I hope to take this chance in Boston Leadership Institute to explore and develop my interetsJ
Some Important Facts About Me (besides being interested in Biology) 1. I am curious about what is going on inside people's brain.
As a sentimental person, I think having a healthy emotional and mental state is crucial for a happy life. More importantly, there are people around me who are tortured by mental illnesses. Therefore, I tend to be very interested in learning about mental health and illnesses. Although I don't have relevant courses at school, I read books and watch movies about those topics, conduct research, and have also started a campaign to help children with Autism.
2. I love drama!
I like watching dramas (all kinds of drama - American, Korean, Chinese...); I like acting out dramas; and I like reading dramas. Drama is like a sanctuary for me and allow me to enter the characters' emotional world, "experience" different personalities, explore different cultures and societies, and somehow even escape from reality;)
3. I like pop music, especially Korean Pop.
I also love pop music from other countries, including China, US, Canada, Sweden... but among all these I have the most passion for Korean Pop music. Mt favorite artist is a girl group called Girls' Generation. I not only like them because of their great music and dances, but more importantly appreciate the journey they have been through since their debut in 2007. At the beginning of their debut they were not liked by many people. There are numerous rumor about them which led them to an extreme downcast. And finally in 2009, their music and spirit brought them to a better situation and now they are the top girl group around Korea. Their spirit really encourage me to face difficulties and failures with hope and always stay optimistic and supportive for other people.
Hope to have a great time with all of you^^
DESIGN PROJECT: BACTERIAL TREATMENT FOR TINEA PEDIS
PROBLEM Dermatophytosis, or ringworm, is a common contagious skin disease caused by fungi known as dermatophytes which belong to a group of organisms that are able to break down the keratin in tissues such as the epidermis, hair, nails, feathers, horns and hooves. Dermatophytosis can be classified into different types based on the specific part of body that the fungi attack. Among the different types, the case in which certain dermatophytes infect the feet is called Tinea pedis, or more commonly known as athlete’s foot. Tinea pedis is noted to be one of the most common types of dermatophtytosis. Reported in 2011, the prevalence of tinea pedis among all forms of dermatophytosis was 20.4% during 2005 to 2010 in a sample of 6,133 patients (Vena, 2012).
All tinea pedis patients suffer damages on the physical appearance and itchy feelings on their feet. Areas that are most commonly infected are the sole and the spaces between toes. Once infected, the feet would become red, cracked, and is often slightly swollen (Centers for Disease Control and Prevention, n.d.). In some cases the skin can also turn white and thicken. There may also be a ring-shaped rash around the skin infected that makes patients feel itchy. In severe cases, the skin on the feet can blister. A more rare kind of tinea pedis causes an acute inflammation, which reddens the skin and forms ulcers (PubMed Health, 2015). The following figure shows how a typical athlete’s foot may look like:
Figure 1. Appearance of Feet Infected by Tinea Pedis (Centers for Disease Control and Prevention, n.d.) Upon all kinds of symptoms tinea pedis leads to, what makes this disease more of a concern is its highly contagious nature. Transmission of the disease can happened due to both direct and indirect contact (National Health Service, n.d.). Because of this, tinea pedis is one of the most common skin infections, affecting approximately 15% to 25% of the world's population in 2009 (Crawford, 2009). Even in developed countries, according to studies made in 2003, tinea pedis has been said to occur in roughly 1 in 5 adults, with a prevalence rate of approximately 10% in 2003 (Nelson, 2003). Despite the development of antifungal agents, the incidence of tinea pedis has still found to be increased over the past two decades (Vena, 2012). This rate is presumably higher in most developing countries whose warm and humid climates are conducive to fungal infection (Nweze, 2010).
COMPETING TECHNOLOGIES As tenia pedis becomes more common around the world, it is clear that an effective treatment is urgently needed to reduce the pain suffered by such a large number of patients. An existing treatment that is often used to address the issue is having antifungal medications to remove the fungi. Two forms of the medication include topical antifungal cream and oral antifungal drugs. Topical antifungal cream is often used to treat comparatively mild tenia pedis and involves rubbing the cream to the specific area infected. Common antifungi used in topical cream includemiconazole nitrate, clotrimazole, tolnaftate, terbinafine hydrochloride, butenafine hydrochloride and undecylenic acid (Wikipedia, n.d.). On the other hand, oral antifungal drugs are often applied to more severe cases or when topical antifungal medication fails. Terbinafine, fluconazole, and itraconazole are three examples of antifungi involved in oral medications (Bell-syer, 2012).
Nevertheless, although research shows that applying antifungal medications is more effective than having no treatment (Bell-syer, 2012), there are problems associated with the usage. One problem with these drugs is that they all require time and patience. The following table shows the result of a study on the effect of two kinds of antifungal cream sold on the market currently, one 1-week treatment and one 4-week treatment:
Table 1. Signs and Symptoms Clearance Rates for Tinea Pedis from Study by Kathleen Fritsch in 2004 (Fritsch Kathleen, 2004) As shown in the table above, for the 1-week treatment, few subjects were cleared of signs and symptoms (especially scaling) at the end of treatment (Week 1).By Week 9, all three symptoms still exist. Similarly, for 4-week treatment, symptoms still exist at the end of the treatment. Even after the treatment, clearance rates for erythema and scaling only improved slightly from week 4 to Week 6. Therefore, it is clear to see that even though antifungal treatments are able to clear symptoms of tinea pedis, it requires patients’ time and patients may still have to suffer those symptoms for weeks after taking the medication.
Furthermore, the highly communicable nature of the disease leads to another weakness of antifungal treatment. That is, only treating the feet is not always enough (Wikipedia, n.d.). Once socks or shoes are worn by the infected feet, there would be a large chance for it to be infested with fungi and wearing them again can reinfect the feet. Thereby, to completely stop tinea pedis, extra efforts are needed clean the objects and areas that were in contact with the infected feet.
Another problem with existing antifungi medications is that as fungi and human cells are both eukaryotes, they share similar characteristics at the biological level. This makes antifungal medicines difficult to target fungi without affecting human cells. As a consequence, many antifungal drugs cause side effects, though mostly mild(Wikipedia, n.d.). For antifungal cream, possible side effects include rash and small skin blister. Less severe side effects involves redness of skin and tingling. (WebMD, n.d.); where as probable side effects of using oral antifungals include feeling sick, abdominal pain, diarrhoea, rash,flatulence, and headache (National Health Service, n.d.). Although liver damage from oral antifungals is rare, but once it occurs it leads to serious effects such as loss of appetite and vomitting. Improper use of both kind of antifungal can lead to severe allergic reaction (swelling of face, neck, or tongue, or difficulty breathing).
DESIGNIdea, Expected Results, Advantages, and DisadvantagesBased on the limitations of the existing solutions discussed above, it is clear that a new type of treatment for the disease would be preferable by patients. The solution I have come up with involves editing bacteria, more specifically Streptococcus pyogenes, which typically colonize the skin and throat areas of the body without causing issues in most cases (About Education, 2015). The way I choose to edit the gene is built upon the characteristic of tinea pedis in which the invading dermatophytes go no deeper than the cornified layer on the skin that composed of a layer of dead cells in the top of the epidermis. The location of the epidermis and the cornified layer are shown in the figure below:
Figure 2. Structure of Skin and Epidermis (Right: A Gunin, n.d.; Left:The Association of the British Pharmaceutical Industry, n.d.)The reason why fungi spread no deeper than over the cornified layer is not known certainty, but it has been speculated that the presence of tranferrin, an iron-binding blood plasma glycoprotein in serum, inhibit fungal propagation to the deeper tissue layers and systematic disease does not occur (Kobayashi, 1996). That’s because iron is involved in a wide variety of important metabolic processes and thus is essential for aerobic life and serves as a nutrient for invading microbial, including dermatophytes (Pouillot, 2013); as transferrin in the serum under the epidermis bind to the iron, it inhibits dermatophytes from growing and invading deeper tissues. On the epidermis, iron is still presented but there is no longer transferrin. (1) This then lead to my first design as a treatment of tinea pedis, which involves inserting tf gene that produces transferrin into S. pyogenes in order prevent people form getting tinea pedis. The following diagram illustrates the overall process of gene transfer:
Figure 3. Overall Process of Gene Transfer The following figure provides a more detailed look at the gene inserted into the bacteria:
Figure 4. Edited S. pyogenes (1) As shown, after being inserted into S.pyogenes with DNA ligase, tf gene works as a part of the bacterial plasmid and will naturally start working. Transcription and translation happens and transferrin will be produced. The transferrin can then be manufactured into a cream and can be rubbed over feet. As transferrin will bind to iron presented on the cornified layer, fungal growth and therefore tinea pedis could be prevented. The expected results are also shown in the truth table below:
Table 2. Truth Table for Design 1 There are several advantages of applying this treatment instead of using traditional medications. First, by applying this treatment, rather than clearing symptoms like antifungal treatments, it prevents the disease at the first place. This reduces the pain that the patients would need to go through from suffering the symptoms and side effects. Besides, the technique of gene transferring is already a relatively well developed by scientists. There were various successful cases, such as genetically modified Bt cotton with pesticidal effects. This makes my design feasible and practical based on current technology. Furthermore, the treatment would expectedly cause few side effects to the body. This is based on two reasons: 1) since there is no transferrin receptor, which is a carrier protein of transferrin (Wikipedia, n.d.) on the cornified layer and is not produced by the bacteria either, even after the transferrin binds to iron the transferrin will not be imported to cells in deeper tissues. Iron overload would not happen typically; 2) as the cells on the cornified layer are dead, they do not present metabolic activities that require iron so iron deficiency would not damage health. Despite the bright sides, there are also limitations of this treatment. One limitation is that as there is no any clinical trials presented, there is still a chance that this treatment could cause unexpected side effects. Further, research shows that to acquire iron, invading microbes have evolved mechanisms to overcome host defense strategies (Nairz, 2010). For instance, Escherichia coli, Klebsiella pneumoniae, and Salmonella species secrete iron chelators, known as siderophores, to compete with transferrin for available iron. If such transferrin cream become more common, it is probable that dermatophytes will also evolve to compete against the transferrin and obtain iron, disrupting the treatment. More importantly, another limitation is that it would be difficult for consumers to control the level of he cream rubbed on the feet. The reason is that iron levels in normal epidermis are thought to vary over a wide range (Molin and Wester, 1976; Kurz et al., 1987) among people due to ages and others body conditions. Thereby, it would be hard to decide the amount of transferrin needed in the cream. If there is no sufficient transferrin binding iron, this treatment would fail to prevent tinea pedis. (2) The difficulty in controlling levels is in fact eliminated in another design that I have come up with. Similarly as the first design, the second design also involves inserting the Tf gene into S. pyogenes and will be rubbed on consumer’s feet as cream. However, an additional receptor and a transcription factor will be needed. Also, unlike design 1, the bacteria in design 2 is not only a media to produce transferrin and will go directly on consumer’s skin.A picture of the edited bacteria can be found below:
Figure 5. Edited S. pyogenes (2) In the bacteria above, there are actually two parts that both can detect the presence of iron – the iron receptor and the iron-sensing transcription factor coded from the gene Fep1 (Pelletier, 2002). The bacteria can then detect iron more sensitively and actively with double sensor provided. With the presence of the iron, the transcription factor will receive the message and will bind to the activator to turn on the Tf gene. Transferrin would then be produced and can bind to the iron presented. Here is a truth table showing the expected results:
Table 3. Truth Table for Design 2 From the table above, it is clear that no transferrin would be produced when there is iron presented. Consequently, adding to the advantages that design 1 has, if the bacteria in this design are applied as treatments there would be no concern regarding controlling the level of cream rubbed. Nonetheless, same as design 1, the problem where unexpected side effects and evolution of fungi may occur still exists. In addition, another problem with the second design is that current technology is not developed enough to have such edited bacteria to be in direct contact with skin. With no precedent before, extra caution is also required in case of side effects. To conclude, although design 2 seems to have advantage over design 1 regarding controlling the level of usage, based on the extent of development of synthetic biology now, design 1 would be safer and more feasible.
Hi everyone! My name is Judy Xu from Shanghai, China. I study at the international department (IB curriculum) of Shanghai World Foreign Language Academy, and will be entering my junior year in fall. In my free time I like to watch TV Dramas/Movies, listen to music, play with coloring books and play badminton.
Biological Research@BLI
I am very passionate about Biology. Especially, I always get fascinated by the emergent property of human bodies where body parts play different roles, but they “corporate” with each other as a system. It seems to me that the unique functions of each body part work like a puzzle – every pieces match with another perfectly. Furthermore, I am also impressed by how the progresses in DNA technologies give tiny double helixes the ability to solve significant problems around us – which is exactly what our course is going to focus on!! Nevertheless, with limited academic opportunities for me to explore my interests in these advanced fields in school, I hope to take this chance in Boston Leadership Institute to explore and develop my interetsJ
Some Important Facts About Me (besides being interested in Biology)
1. I am curious about what is going on inside people's brain.
As a sentimental person, I think having a healthy emotional and mental state is crucial for a happy life. More importantly, there are people around me who are tortured by mental illnesses. Therefore, I tend to be very interested in learning about mental health and illnesses. Although I don't have relevant courses at school, I read books and watch movies about those topics, conduct research, and have also started a campaign to help children with Autism.
2. I love drama!
I like watching dramas (all kinds of drama - American, Korean, Chinese...); I like acting out dramas; and I like reading dramas. Drama is like a sanctuary for me and allow me to enter the characters' emotional world, "experience" different personalities, explore different cultures and societies, and somehow even escape from reality;)
3. I like pop music, especially Korean Pop.
I also love pop music from other countries, including China, US, Canada, Sweden... but among all these I have the most passion for Korean Pop music. Mt favorite artist is a girl group called Girls' Generation. I not only like them because of their great music and dances, but more importantly appreciate the journey they have been through since their debut in 2007. At the beginning of their debut they were not liked by many people. There are numerous rumor about them which led them to an extreme downcast. And finally in 2009, their music and spirit brought them to a better situation and now they are the top girl group around Korea. Their spirit really encourage me to face difficulties and failures with hope and always stay optimistic and supportive for other people.
Hope to have a great time with all of you^^
DESIGN PROJECT: BACTERIAL TREATMENT FOR TINEA PEDIS
PROBLEM
Dermatophytosis, or ringworm, is a common contagious skin disease caused by fungi known as dermatophytes which belong to a group of organisms that are able to break down the keratin in tissues such as the epidermis, hair, nails, feathers, horns and hooves. Dermatophytosis can be classified into different types based on the specific part of body that the fungi attack. Among the different types, the case in which certain dermatophytes infect the feet is called Tinea pedis, or more commonly known as athlete’s foot. Tinea pedis is noted to be one of the most common types of dermatophtytosis. Reported in 2011, the prevalence of tinea pedis among all forms of dermatophytosis was 20.4% during 2005 to 2010 in a sample of 6,133 patients (Vena, 2012).
All tinea pedis patients suffer damages on the physical appearance and itchy feelings on their feet. Areas that are most commonly infected are the sole and the spaces between toes. Once infected, the feet would become red, cracked, and is often slightly swollen (Centers for Disease Control and Prevention, n.d.). In some cases the skin can also turn white and thicken. There may also be a ring-shaped rash around the skin infected that makes patients feel itchy. In severe cases, the skin on the feet can blister. A more rare kind of tinea pedis causes an acute inflammation, which reddens the skin and forms ulcers (PubMed Health, 2015). The following figure shows how a typical athlete’s foot may look like:
Figure 1. Appearance of Feet Infected by Tinea Pedis
(Centers for Disease Control and Prevention, n.d.)
Upon all kinds of symptoms tinea pedis leads to, what makes this disease more of a concern is its highly contagious nature. Transmission of the disease can happened due to both direct and indirect contact (National Health Service, n.d.). Because of this, tinea pedis is one of the most common skin infections, affecting approximately 15% to 25% of the world's population in 2009 (Crawford, 2009). Even in developed countries, according to studies made in 2003, tinea pedis has been said to occur in roughly 1 in 5 adults, with a prevalence rate of approximately 10% in 2003 (Nelson, 2003). Despite the development of antifungal agents, the incidence of tinea pedis has still found to be increased over the past two decades (Vena, 2012). This rate is presumably higher in most developing countries whose warm and humid climates are conducive to fungal infection (Nweze, 2010).
COMPETING TECHNOLOGIES
As tenia pedis becomes more common around the world, it is clear that an effective treatment is urgently needed to reduce the pain suffered by such a large number of patients. An existing treatment that is often used to address the issue is having antifungal medications to remove the fungi. Two forms of the medication include topical antifungal cream and oral antifungal drugs. Topical antifungal cream is often used to treat comparatively mild tenia pedis and involves rubbing the cream to the specific area infected. Common antifungi used in topical cream includemiconazole nitrate, clotrimazole, tolnaftate, terbinafine hydrochloride, butenafine hydrochloride and undecylenic acid (Wikipedia, n.d.). On the other hand, oral antifungal drugs are often applied to more severe cases or when topical antifungal medication fails. Terbinafine, fluconazole, and itraconazole are three examples of antifungi involved in oral medications (Bell-syer, 2012).
Nevertheless, although research shows that applying antifungal medications is more effective than having no treatment (Bell-syer, 2012), there are problems associated with the usage. One problem with these drugs is that they all require time and patience. The following table shows the result of a study on the effect of two kinds of antifungal cream sold on the market currently, one 1-week treatment and one 4-week treatment:
As shown in the table above, for the 1-week treatment, few subjects were cleared of signs and symptoms (especially scaling) at the end of treatment (Week 1).By Week 9, all three symptoms still exist. Similarly, for 4-week treatment, symptoms still exist at the end of the treatment. Even after the treatment, clearance rates for erythema and scaling only improved slightly from week 4 to Week 6. Therefore, it is clear to see that even though antifungal treatments are able to clear symptoms of tinea pedis, it requires patients’ time and patients may still have to suffer those symptoms for weeks after taking the medication.
Furthermore, the highly communicable nature of the disease leads to another weakness of antifungal treatment. That is, only treating the feet is not always enough (Wikipedia, n.d.). Once socks or shoes are worn by the infected feet, there would be a large chance for it to be infested with fungi and wearing them again can reinfect the feet. Thereby, to completely stop tinea pedis, extra efforts are needed clean the objects and areas that were in contact with the infected feet.
Another problem with existing antifungi medications is that as fungi and human cells are both eukaryotes, they share similar characteristics at the biological level. This makes antifungal medicines difficult to target fungi without affecting human cells. As a consequence, many antifungal drugs cause side effects, though mostly mild(Wikipedia, n.d.). For antifungal cream, possible side effects include rash and small skin blister. Less severe side effects involves redness of skin and tingling. (WebMD, n.d.); where as probable side effects of using oral antifungals include feeling sick, abdominal pain, diarrhoea, rash,flatulence, and headache (National Health Service, n.d.). Although liver damage from oral antifungals is rare, but once it occurs it leads to serious effects such as loss of appetite and vomitting. Improper use of both kind of antifungal can lead to severe allergic reaction (swelling of face, neck, or tongue, or difficulty breathing).
DESIGNIdea, Expected Results, Advantages, and DisadvantagesBased on the limitations of the existing solutions discussed above, it is clear that a new type of treatment for the disease would be preferable by patients. The solution I have come up with involves editing bacteria, more specifically Streptococcus pyogenes, which typically colonize the skin and throat areas of the body without causing issues in most cases (About Education, 2015). The way I choose to edit the gene is built upon the characteristic of tinea pedis in which the invading dermatophytes go no deeper than the cornified layer on the skin that composed of a layer of dead cells in the top of the epidermis. The location of the epidermis and the cornified layer are shown in the figure below:
Figure 2. Structure of Skin and Epidermis
(Right: A Gunin, n.d.; Left:The Association of the British Pharmaceutical Industry, n.d.)The reason why fungi spread no deeper than over the cornified layer is not known certainty, but it has been speculated that the presence of tranferrin, an iron-binding blood plasma glycoprotein in serum, inhibit fungal propagation to the deeper tissue layers and systematic disease does not occur (Kobayashi, 1996). That’s because iron is involved in a wide variety of important metabolic processes and thus is essential for aerobic life and serves as a nutrient for invading microbial, including dermatophytes (Pouillot, 2013); as transferrin in the serum under the epidermis bind to the iron, it inhibits dermatophytes from growing and invading deeper tissues. On the epidermis, iron is still presented but there is no longer transferrin.
(1)
This then lead to my first design as a treatment of tinea pedis, which involves inserting tf gene that produces transferrin into S. pyogenes in order prevent people form getting tinea pedis. The following diagram illustrates the overall process of gene transfer:
Figure 3. Overall Process of Gene Transfer
The following figure provides a more detailed look at the gene inserted into the bacteria:
Figure 4. Edited S. pyogenes (1)
As shown, after being inserted into S.pyogenes with DNA ligase, tf gene works as a part of the bacterial plasmid and will naturally start working. Transcription and translation happens and transferrin will be produced. The transferrin can then be manufactured into a cream and can be rubbed over feet. As transferrin will bind to iron presented on the cornified layer, fungal growth and therefore tinea pedis could be prevented. The expected results are also shown in the truth table below:
There are several advantages of applying this treatment instead of using traditional medications. First, by applying this treatment, rather than clearing symptoms like antifungal treatments, it prevents the disease at the first place. This reduces the pain that the patients would need to go through from suffering the symptoms and side effects. Besides, the technique of gene transferring is already a relatively well developed by scientists. There were various successful cases, such as genetically modified Bt cotton with pesticidal effects. This makes my design feasible and practical based on current technology. Furthermore, the treatment would expectedly cause few side effects to the body. This is based on two reasons: 1) since there is no transferrin receptor, which is a carrier protein of transferrin (Wikipedia, n.d.) on the cornified layer and is not produced by the bacteria either, even after the transferrin binds to iron the transferrin will not be imported to cells in deeper tissues. Iron overload would not happen typically; 2) as the cells on the cornified layer are dead, they do not present metabolic activities that require iron so iron deficiency would not damage health.
Despite the bright sides, there are also limitations of this treatment. One limitation is that as there is no any clinical trials presented, there is still a chance that this treatment could cause unexpected side effects. Further, research shows that to acquire iron, invading microbes have evolved mechanisms to overcome host defense strategies (Nairz, 2010). For instance, Escherichia coli, Klebsiella pneumoniae, and Salmonella species secrete iron chelators, known as siderophores, to compete with transferrin for available iron. If such transferrin cream become more common, it is probable that dermatophytes will also evolve to compete against the transferrin and obtain iron, disrupting the treatment. More importantly, another limitation is that it would be difficult for consumers to control the level of he cream rubbed on the feet. The reason is that iron levels in normal epidermis are thought to vary over a wide range (Molin and Wester, 1976; Kurz et al., 1987) among people due to ages and others body conditions. Thereby, it would be hard to decide the amount of transferrin needed in the cream. If there is no sufficient transferrin binding iron, this treatment would fail to prevent tinea pedis.
(2)
The difficulty in controlling levels is in fact eliminated in another design that I have come up with. Similarly as the first design, the second design also involves inserting the Tf gene into S. pyogenes and will be rubbed on consumer’s feet as cream. However, an additional receptor and a transcription factor will be needed. Also, unlike design 1, the bacteria in design 2 is not only a media to produce transferrin and will go directly on consumer’s skin.A picture of the edited bacteria can be found below:
Figure 5. Edited S. pyogenes (2)
In the bacteria above, there are actually two parts that both can detect the presence of iron – the iron receptor and the iron-sensing transcription factor coded from the gene Fep1 (Pelletier, 2002). The bacteria can then detect iron more sensitively and actively with double sensor provided. With the presence of the iron, the transcription factor will receive the message and will bind to the activator to turn on the Tf gene. Transferrin would then be produced and can bind to the iron presented. Here is a truth table showing the expected results:
Table 3. Truth Table for Design 2
From the table above, it is clear that no transferrin would be produced when there is iron presented. Consequently, adding to the advantages that design 1 has, if the bacteria in this design are applied as treatments there would be no concern regarding controlling the level of cream rubbed.
Nonetheless, same as design 1, the problem where unexpected side effects and evolution of fungi may occur still exists. In addition, another problem with the second design is that current technology is not developed enough to have such edited bacteria to be in direct contact with skin. With no precedent before, extra caution is also required in case of side effects.
To conclude, although design 2 seems to have advantage over design 1 regarding controlling the level of usage, based on the extent of development of synthetic biology now, design 1 would be safer and more feasible.
TESTING
In-lab testing is needed to see if iron is still observed with each edited bacteria presented. If the binding with iron is successful, the next step can be to apply the real dermatophytes in the tests to see if the bacteria is able to stop their growth. Such tests can help scientists to examine the efficiency of each bacteria. If the efficiency found is high, producers could consider to manufacture the transferrin/bacteria into forms other than cream that can adapt to body regions affected by other types of dermatophytosis, such as scalp.
Other testings can include testing the average iron content in people with different ages or body conditions (e.d. pregnancy), as well as testing the amount of transferrin needed to bind those amounts of iron. After enough trials, scientists could be able to determine a ratio between the amount of iron and the amount of transferrin needed to bind it. This can improve design 1 by allowing pharmacists to give suggestions to different groups of people about the appropriate amount of usage of the cream.
BIBLIOGRAPHYJOURNALS + WEBSITES
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2907807/
http://www.cdc.gov/healthywater/hygiene/disease/athletes_foot.html
http://www.cfsph.iastate.edu/Factsheets/pdfs/dermatophytosis.pdf
http://www.newmicrobiologica.org/PUB/allegati_pdf/2012/2/207.pdf
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0072733/
http://www.cdc.gov/fungal/diseases/ringworm/symptoms.html
http://www.nhs.uk/Conditions/Athletes-foot/Pages/Introduction.aspx
https://en.wikipedia.org/wiki/Antifungal
http://www.webmd.com/drugs/2/drug-61279/antifungal-cream-topical/details/list-sideeffects
http://www.nhs.uk/Conditions/Antifungal-drugs/Pages/Side-effects.aspx
https://en.wikipedia.org/wiki/Athlete%27s_foot#cite_note-Crawford_2007-31
http://biology.about.com/od/microbiology/tp/Bacteria-That-Live-on-Your-Skin.htm
http://www.fda.gov/ohrms/dockets/ac/04/briefing/4036B1_05_Study%20DesignTinea%20Pedis.htm
http://www.ncbi.nlm.nih.gov/books/NBK8103/
http://www.ncbi.nlm.nih.gov/pubmed/23866012
http://www.ncbi.nlm.nih.gov/pubmed/11956219
Nairz M, Schroll A, Sonnweber T, Weiss G. The struggle for iron -- a metal at the host-pathogen interface. Cell Microbiol. 2010;12:1691-1702.
Vena GA, Chieco P, Posa F, Garafolo A, Bosco A, Cassano N. Epidemiology of dermatophytoses:retrospective analysis from 2005 to 2010 and comparison with previous data from 1975. New Microbiologica 2012;35(2):207-13. [MEDLINE: 22707134]
Nelson MM, Martin AG, Hefferman MP. Superficial Fungal Infections: Dermatophytosis, Onychomytosis, Tinea Nigra, Piedra. In: Fitzpatrick TB editor(s). Dermatology in General Medicine. 6th Edition. New York: McGraw-Hill, 2003:1989-2005.
Nweze EI. Dermatophytosis in Western Africa: A Review. Pakistan Journal of Biological Sciences 2010;13(13):649-56. [MEDLINE: 21717868]
Bell-Syer, SE; Khan, SM; Torgerson, DJ (17 October 2012). Bell-Syer, Sally EM, ed. "Oral treatments for fungal infections of the skin of the foot". The Cochrane database of systematic reviews. 10: CD003584. doi:10.1002/14651858.CD003584.pub2. PMID 23076898.
Molin L., Wester P. O. (1976). The estimated daily loss of trace elements from normal skin by desquamation. Scand. J. Clin. Lab. Investig. 36 679–682 10.3109/00365517609054495
Kurz K., Steigleder G. K., Bischof W., Gonsior B. (1987). PIXE analysis in different stages of psoriatic skin. J. Investig. Dermatol. 88 223–226 10.1111/1523-1747.ep12525385
PICTURES
http://www.histol.ru/atlas-en/content-en.htm
http://www.abpischools.org.uk/page/modules/homeostasis_sugar/sugar5.cfm?coSiteNavigation_allTopic=1
https://www.amazon.com/Karter-Scientific-206D2-Plastic-Sterile/dp/B005Z4QU5U?ie=UTF8&*Version*=1&*entries*=0&ref_=redir_mobile_desktop
http://www.freeimages.com/premium/cartoon-toothpaste-577062
https://en.wikipedia.org/wiki/Transferrin_receptor
https://en.wikipedia.org/wiki/Transferrin#/media/File:Protein_TF_PDB_1a8e.png